1. Field of the Invention
The present invention relates generally to a hand tool, and more particularly to a torque wrench with warning function.
2. Description of the Related Art
Along with the advance of industries, higher and higher precision of tightening force for threaded members is required. To catch up with the requirement, various wrenches with torque value reminding function have been developed and released to the market.
The applicant's Taiwan Patent No. I316890 discloses a colored warning structure of electronic torque tool. The torque tool has a wrench main body on which a display screen is disposed. In the case that a certain operation value does not reach a preset range, the display module will emit a first colored light to indicate the current value. When the operation value becomes approximate to the preset range, the display module will go a second colored light instead so as to indicate the current value. When the operation value exceeds the preset range, the display module will immediately go a third colored light instead of the second colored light to indicate the current value. It provides a warning and reminding effect, and advantages the electronic tool applicable in any working site without limitation. Moreover, the light with different colors can attract an operator's attention. In addition, the light intensity is sequentially progressively increased to remind the operator to note the change of the operation value.
Taiwan Patent Publication No. 201117928 discloses a colored light warning method for digital torque tool. The digital torque tool has a main body on which an operation unit and a display unit are disposed. According to different percentages of a preset reference torque value, the operation unit can be respectively set with several comparison modes correspondingly connected to the display unit. In Publication No. 201117928, the comparison modes are respectively set as the ranges of below 80%, 80%˜100% and over 100% of the preset reference torque value. Therefore, the display unit can emit different colors of light according to the different comparison modes respectively for a user to judge in which value range the current wrenching torque falls so as to facilitate the operation.
In addition, Taiwan Utility Model No. M360114 discloses an integrated numerically controlled tool. The tool is a wrench having a numerically controlled display system and multiple light-emitting diodes (LED) display elements. The LED display elements can sequentially emit light to indicate the current torque value state of the wrench to a user so as to achieve a warning effect.
All the above conventional wrenches will give the warning only when the torque value becomes approximate to the preset value without taking into consideration how close to the preset value the torque value becomes. In general, the conventional wrench has a rough warning range with respect to the preset value. For example, in Taiwan Patent No. I316890, an operator is reminded that the current torque is closer and closer to the preset value. However, as to the requirement for higher precision in torque to meet, the rough warning range provided by the conventional wrench is actually helpless to the operator. For example, in Taiwan Patent Publication No. 201117928, the torque warning start point is too early so that the operator will focus on the torque value too early. Under such circumstance, the perception of the operator to the warning will gradually decline with the time so that the operator will become more and more feeless. In Taiwan Utility Model No. M360114, the torque value state is indicated by the number of the LED display elements to achieve a torque warning effect. Such arrangement can hardly precisely tell when the torque value will reach the preset value. Therefore, an operator cannot precisely stop the operation at a proper time.
It can be known from the above that the conventional techniques have the shortcomings of too early warning point, too large warning range and vague warning effect. As a result, an operator is very likely to misjudge when the desired torque is reached.
It is therefore tried by the applicant to provide a torque warning hand tool, which h has a precise and effective warning range to truly provide a warning effect so as to avoid misjudgment of an operator.